Apparatus for generating electrical energy and method for manufacturing the same

ABSTRACT

An apparatus for generating electrical energy may include; a first electrode, a second electrode spaced apart from the first electrode, a nanowire which includes a piezoelectric material and is disposed on the first electrode, an active layer disposed on the first electrode, a conductive layer disposed on the active layer, and an insulating film disposed between the conductive layer and the nanowire, wherein the nanowire and the active layer are electrically connected to each other. A method for manufacturing an apparatus for generating electrical energy may include; disposing a nanowire including a piezoelectric material on a first electrode, disposing an active layer, which is electrically connected to the nanowire, on the first electrode, disposing an insulating film on the nanowire, disposing a conductive layer on the active layer, and disposing a second electrode in proximity to the nanowire and substantially opposite to the first electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No.10-2009-0029584, filed on Apr. 6, 2009, and all the benefits accruingtherefrom under 35 U.S.C. §119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND

1. Field

Disclosed herein are an apparatus for generating electrical energy and amethod for manufacturing the apparatus for generating electrical energy.

2. Description of the Related Art

With the recent advent of miniaturized high-performance devices in thefield of electronics, the development and use of nanoscale devices havebecome more prevalent. In order to manufacture nanodevices, a techniqueof producing nanowires has been previously developed. A nanowire istypically a wire with a diameter of several tens of nanometers. Thenanowire may have an aspect ratio from about 10 to about severalthousands, e.g., the length of the nanowires may be from about 10 times,to several thousand times, its width.

The nanowire may have electrical, chemical, physical and opticalproperties that are different from the general properties of the samematerial when it is in bulk form. Increasingly miniaturized andintegrated devices may be implemented using the molecular properties ofthe nanowires in conjunction with some of the bulk properties thereof.Nanowires may be used in various fields such as laser, transistor,memory, sensor, and other similar applications.

More recently, miniaturization is being combined with versatility andmobility to produce mobile devices that can perform a variety ofdifferent functions. In order to produce sustainable mobile devices,batteries having an adequate power supply are desirable. However, thedevelopment of battery capacity for power supply presently lags behindthe integration of functionality into these mobile devices. Therefore,the use of an auxiliary battery is desirable, and the development of theauxiliary battery for use as an emergency power source, and theenablement of a wireless rechargeability may also be desirable.

SUMMARY

Disclosed herein are an apparatus for generating electrical energy whichmay generate electrical energy by absorbing light such as sunlight or inresponse to an applied stress or signal in the case where the light isunavailable, and a method for manufacturing the apparatus for generatingelectrical energy.

An exemplary embodiment of an apparatus for generating electrical energyincludes; a first electrode, a second electrode spaced apart from thefirst electrode, a nanowire which includes a piezoelectric material andis disposed on the first electrode, an active layer disposed on thefirst electrode, a conductive layer disposed on the active layer, and aninsulating film disposed between the conductive layer and the nanowire,wherein the nanowire and the active layer may be electrically connectedto each other.

An exemplary embodiment of a method for manufacturing an apparatus forgenerating electrical energy includes; disposing a nanowire including apiezoelectric material on a first electrode, disposing an active layer,which is electrically connected to the nanowire, on the first electrode,disposing an insulating film on the nanowire, disposing a conductivelayer on the active layer, and disposing a second electrode in proximityto the nanowire and substantially opposite to the first electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the disclosedexemplary embodiments will be more apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a front perspective view illustrating an exemplary embodimentof an apparatus for generating electrical energy;

FIG. 2A is a cross-sectional view illustrating an exemplary embodimentof an apparatus for generating electrical energy;

FIG. 2B is a cross-sectional view illustrating an exemplary embodimentof an apparatus for generating electrical energy to which a stress isapplied;

FIG. 3A(i) is a cross-sectional view illustrating another exemplaryembodiment of an apparatus for generating electrical energy;

FIG. 3A(ii) is an enlarged view of the area 3A(ii) of FIG. 3A(i);

FIG. 3B(i) is a cross-sectional view illustrating an exemplaryembodiment of an apparatus for generating electrical energy to which asignal is applied such that the nanowire resonates;

FIG. 3B(ii) is an enlarged view of the area 3A(ii) of FIG. 3B(i);

FIGS. 4A to 4F are cross-sectional views illustrating processes of anexemplary embodiment of a method for manufacturing an exemplaryembodiment of an apparatus for generating electrical energy;

FIGS. 5A to 5G are cross-sectional views illustrating additionalprocesses of an exemplary embodiment of a method for manufacturing anexemplary embodiment of an apparatus for generating electrical energy;and

FIGS. 6A(i), 6A(ii) and 6B are cross-sectional views illustrating stilladditional processes of an exemplary embodiment of a method formanufacturing an exemplary embodiment of an apparatus for generatingelectrical energy.

DETAILED DESCRIPTION

Exemplary embodiments now will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsare shown. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the exemplaryembodiments set forth therein. Rather, these exemplary embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of this disclosure to those skilled in the art.In the description, details of well-known features and techniques may beomitted to avoid unnecessarily obscuring the presented exemplaryembodiments.

It will be understood that when an element is referred to as being “on”another element, it can be directly on the other element or interveningelements may be present therebetween. In contrast, when an element isreferred to as being “directly on” another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of the present invention.

The terminology used herein is for the purpose of describing particularexemplary embodiments only and is not intended to be limiting of thisdisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. Furthermore, the use of the terms a, an, etc. donot denote a limitation of quantity, but rather denote the presence ofat least one of the referenced item. It will be further understood thatthe terms “comprises” and/or “comprising”, or “includes” and/or“including” when used in this specification, specify the presence ofstated features, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother elements as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower”, can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art. It will be further understood that terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and the present disclosure, and will notbe interpreted in an idealized or overly formal sense unless expresslyso defined herein.

Exemplary embodiments of the present invention are described herein withreference to cross section illustrations that are schematicillustrations of idealized embodiments of the present invention. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the present invention should not beconstrued as limited to the particular shapes of regions illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present invention.

All methods described herein can be performed in a suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “suchas”), is intended merely to better illustrate the invention and does notpose a limitation on the scope of the invention unless otherwiseclaimed. No language in the specification should be construed asindicating any non-claimed element as essential to the practice of theinvention as used herein.

Hereinafter, the present invention will be described in detail withreference to the accompanying drawings.

FIG. 1 is a front perspective view illustrating an exemplary embodimentof an apparatus for generating electrical energy.

Referring to FIG. 1, the apparatus for generating electric energy mayinclude a first electrode 10, a second electrode 20, a nanowire 30, anactive layer 40, an insulation film 50, and a conductive layer 60.

The first electrode 10 is a lower electrode, which supports the nanowire30 thereon. In one exemplary embodiment, the first electrode 10 may beformed on a substrate 1. For example, in one exemplary embodiment thefirst electrode 10 may be formed as a metal film or a ceramic elementexhibiting conductivity. In such an exemplary embodiment, the firstelectrode 10 is formed on the substrate 1. Exemplary embodiments of thesubstrate 1 may be formed of glass, silicon (Si), polymer, sapphire,gallium nitride (GaN), silicon carbide (SiC), or other materials havingsimilar characteristics.

The second electrode 20 may be spaced apart from the first electrode 10.Similarly to the first electrode 10, exemplary embodiments includeconfigurations wherein the second electrode 20 may be formed on asubstrate 2. For example, in one exemplary embodiment the first and thesecond electrodes 10 and 20 may be formed by forming conductivematerials on the respective substrates 1 and 2 by plating, sputtering,e-beam evaporation, thermal evaporation, or other similar methods.

The first and the second electrodes 10 and 20 may include at least oneof a metal, indium tin oxide (“ITO”), carbon nanotubes (“CNTs”),graphene, conductive polymer, nanofibers, nanocomposites, othermaterials having similar characteristics and a combination thereof. Inan exemplary embodiment wherein the first and second electrodes areformed from metal, the metal may be at least one of a gold-palladium(Au—Pd) alloy, gold (Au), palladium (Pd), platinum (Pt), ruthenium (Ru),other materials with similar characteristics and a combination thereof.

In one exemplary embodiment, at least one of the first and the secondelectrodes 10 and 20 may be made of a transparent material. Furthermore,exemplary embodiments include configurations wherein at least one of thefirst and the second electrodes 10 and 20 may be made of a flexibleelectrode which may be deformed by an applied stress. The application ofstresses to the substrates 1 and 2 will be described in more detailbelow with respect to FIG. 2B.

Exemplary embodiments of the substrates 1 and 2 on which the first andthe second electrodes 10 and 20 are formed, respectively, may also bemade of a transparent material such as a glass, polymer or othermaterial with similar characteristics. Further, each of the substrates 1and 2 may be made of a flexible material which may be deformed by anapplied stress.

One or more nanowires 30 may be disposed on the first electrode 10.Exemplary embodiments of the nanowire 30 may be made of a piezoelectricmaterial in which a potential difference is generated when physicallydeformed. For example, in one exemplary embodiment the nanowire mayinclude at least one of a zinc oxide (ZnO), lead-zirconate-titanate(“PZT”), barium titanate (BaTiO₃), other piezoelectric materials withsimilar characteristics and a combination thereof.

The nanowire 30 may be grown on the first electrode 10. Growing thenanowire 30 on the first electrode 10 rather than directly on thesubstrate 1 may present several advantages. In an exemplary embodiment,a conductivity of a nanowire energy generating system may be improvedover an embodiment wherein the nanowires is grown directly on thesubstrate 1, since the nanowire 30 is formed on the conductive firstelectrode 10. Furthermore, it may become easier to control the growth ofthe nanowire 30, e.g., the nanowire 30 may be grown vertically on thefirst electrode 10. Furthermore, a uniformity of the shapes orlongitudinal directions of the nanowires 30 may be improved.

In the present exemplary embodiment, the nanowire 30 may extend in adirection substantially perpendicular to the surfaces of the first andthe second electrodes 10 and 20. Alternative exemplary embodimentsinclude configurations wherein the nanowire 30 may extend to be inclinedin a direction which is not substantially perpendicular to the surfacesof the first and the second electrodes 10 and 20. The number of thenanowires 30 illustrated in the figures is only an example, and thenumber of the nanowires 30 may be varied depending on the size andapplications of the apparatus, e.g., exemplary embodiments includeconfigurations with additional or fewer nanowires 30 than thatillustrated in FIG. 1.

The active layer 40 may be disposed on the first electrode 10 on whichthe nanowire 30 is formed. After forming one or more nanowires 30 on thefirst electrode 10, the active layer 40 may be formed on substantiallythe entire surface of the first electrode 10. As a result, the one ormore nanowires 30 may be disposed to penetrate the active layer 40. Theactive layer 40 and the nanowire 30 may be electrically connected toeach other, e.g., they may be electrically connected via an outersurface of the nanowire 30 disposed in contact with the active layer 40.

Exemplary embodiments of the active layer 40 may include an organicmaterial, an inorganic material, an organic-inorganic composite, orother materials with similar characteristics. For example, in oneexemplary embodiment the inorganic material which may be used for theactive layer 40 may include silicon or a compound semiconductor such ascopper indium gallium (di)selenide (“CIGS”). Furthermore, in oneexemplary embodiment the organic material which may be used for theactive layer 40 may include a dye-sensitized material such an oxidesemiconductor on which a dye molecule is adsorbed.

In one exemplary embodiment, the conductive layer 60 may be disposed onthe active layer 40. Exemplary embodiments of the conductive layer 60may be made of metal or other conductive materials having similarcharacteristics. For example, in one exemplary embodiment the conductivelayer 60 may include at least one of a metal, ITO, CNT, graphene,conductive polymer, nanofibers, nanocomposite, other materials havingsimilar characteristics and a combination thereof. In the exemplaryembodiment wherein the conductive layer 60 is the metal, at least one ofAuPd, Au, Pd, Pt, Ru, other materials having similar characteristics anda combination thereof may be used. In an exemplary embodiment, theconductive layer 60 may be made of a transparent material. Furthermore,exemplary embodiments include configurations wherein the conductivelayer 60 may be made of a flexible material which may be deformed by astress.

In one exemplary embodiment, the insulating film 50 may be disposedbetween the conductive layer 60 and the nanowire 30. In such anexemplary embodiment, the insulating film 50 may be formed to surroundthe surfaces of the nanowire 30. Since the insulating film 50 is formedof a nonconductive material, the conductive layer 60 and the nanowire 30may be electrically separated by the insulating film 50.

In an exemplary embodiment, the insulating film 50 may be made of apiezoelectric material similarly to the nanowire 30. For example, in oneexemplary embodiment the insulating film 50 may include at least one ofPZT, BaTiO₃, other piezoelectric materials having similarcharacteristics and a combination thereof. Since the insulating film 50is made of the piezoelectric material, the nanowire 30 is electricallyseparated from the conductive layer 60, and at the same time, thepiezoelectric characteristics of the nanowire 30 may be improved by theinsulating film 50.

When light, such as sunlight, is incident on the apparatus forgenerating electrical energy, the active layer 40 absorbs the light togenerate an electrical energy. The active layer 40 may be electricallyconnected to the conductive layer 60, and may also be electricallyconnected to the first electrode 10 by way of the nanowire 30, i.e., theportion of the nanowire 30 disposed within the active layer 40 and notsurrounded by the insulation film 50. When the first electrode 10 andthe conductive material 60 are electrically connected using a conductivematerial, current may flow though a closed-circuit including the firstelectrode 10, the active layer 40, and the conductive layer 60. In anexemplary embodiment, a first storage device 70 may be electricallyconnected between the first electrode 10 and the conductive layer 60 tostore the electrical energy generated from the active layer 40.Exemplary embodiments of the first storage device 70 include capacitorsand batteries and other storage media.

As shown in FIG. 2B, when a stress is applied to the apparatus forgenerating electrical energy, the nanowire 30 made of the piezoelectricmaterial may be deformed and an electric potential may be generated inthe nanowire 30. Furthermore, the deformed nanowire 30 may be in contactwith the second electrode 20. When the first and the second electrodes10 and 20 are electrically connected using a conductive material, e.g.the nanowire 30, current may flow through a closed-circuit including thefirst electrode 10, the nanowire 30, and the second electrode 20. In anexemplary embodiment, a second storage device 80 may be electricallyconnected between the first and the second electrodes 10 and 20 to storethe electrical energy generated from the nanowire 30. Exemplaryembodiments of the second storage device 80 include capacitors andbatteries and other storage media.

As described above, the first and the second storage devices 70 and 80may include a rechargeable battery, capacitor, or other suitable meansfor storing electrical energy. For example, in one exemplary embodimentthe first and the second storage devices 70 and 80 may include anickel-cadmium battery, a nickel-hydrogen battery, a lithium ionbattery, a lithium polymer battery or other battery having similarcharacteristics. Furthermore, the first and the second storage devices70 and 80 may further include an amplifier (not shown) for amplifyingvoltage.

The apparatus for generating electrical energy described above maygenerate electrical energy by absorbing incident light, or in responseto an applied stress, or both. By forming at least one of the first andsecond electrodes 10 and 20 of the apparatus for generating electricalenergy in an array type, a touch sensor which may detect a positionwhere the stress is applied may be implemented. Furthermore, byelectrically connecting a plurality of the apparatuses for generatingelectrical energy in an array type, the electrical energy generated fromthe apparatuses for generating electrical energy may be amplified.

FIG. 2 a is a cross-sectional view illustrating an exemplary embodimentof an apparatus for generating electrical energy. With reference to FIG.2 a, operations of the active layer 40 in the apparatus for generatingelectrical energy will be described in detail.

When light such as sunlight is incident on the apparatus for generatingelectrical energy, part or all of the incident light may reach theactive layer 40. At least one of the first electrode 10, the secondelectrode 20 and the conductive layer 60 may be made of a transparentmaterial to allow sunlight to reach the active layer 40. Furthermore,the substrates 1 and 2 on which the first and the second electrodes 10and 20 are formed, respectively, may be made of a transparent material.

When electrons in the active layer 40 absorb energy from the incidentlight, excitons in the excited state may be formed. The exciton may beseparated into an electron 1000 and a hole 2000 due to anelectromagnetic field produced by a difference in work function betweenmaterials adjacent to the active layer 40. Then, the electron 1000 andthe hole 2000 may be moved in different, e.g., opposite, directions bythe electromagnetic field. For example, the electron 1000 may be movedfrom the active layer 40 toward the first electrode 10 through thenanowire 30, and the hole 2000 may be moved from the active layer 40toward the conductive layer 60.

Accordingly, an electric potential difference may be generated betweenthe first electrode 10 and the conductive layer 60. When the firstelectrode 10 and the conductive layer 60 are electrically connectedusing the active layer 40 and a first storage device 70, current mayflow through a closed-circuit including the first electrode 10, theactive layer 40, and the conductive layer 60. In an exemplaryembodiment, by electrically connecting a first storage device 70 betweenthe first electrode 10 and the conductive 60, electrical energygenerated by the active layer 40 may be stored in the first storagedevice 70.

Light may be incident on the active layer 40 from an upper portion or alower portion, or both, of the apparatus for generating electricalenergy. In the exemplary embodiment where the light is incident on theactive layer 40 from the upper portion of the apparatus for generatingelectrical energy, electrical energy generation efficiency of the activelayer 40 may be improved by inducing focusing of the incident lightusing the at least one nanowires 30.

As described above, when light, such as sunlight, is incident on theapparatus for generating electrical energy according to an exemplaryembodiment, electrical energy may be generated as the active layer 40absorbs the light. Furthermore, the generated electrical energy may bestored in the first storage device 70.

FIG. 2B is a cross-sectional view illustrating an exemplary embodimentof an apparatus for generating electrical energy to which a stress isapplied. With reference to FIG. 2B, operations of the nanowire 30 of theapparatus for generating electrical energy will be described in detail.

While a stress is not applied to the apparatus for generating electricalenergy, the nanowire 30 may be spaced apart from the second electrode 20by a distance “d”. The distance d between the nanowire 30 and the secondelectrode 20 may be determined to be a distance that the nanowire 30comes in contact with the second electrode 20 when a stress is appliedto the second or the first electrode 20 or 10. Alternative exemplaryembodiments include configurations wherein the nanowire 30 may be incontact with the second electrode 20 while a stress is not applied,e.g., the distance “d” maybe zero.

As a stress is applied to a portion B of the apparatus for generatingelectrical energy, the second electrode 20 and the substrate 2 may bebent downward. As a result, the distance between the first and thesecond electrodes 10 and 20 decreases, so that the nanowire 30 disposedin the portion B may be pressed and deformed. Since the nanowire 30 ismade of the piezoelectric material, an electric potential difference isgenerated in the deformed nanowire 30.

When the first and the second electrodes 10 and 20 are electricallyconnected using a conductive material, e.g., the nanowire 30, currentmay flow through the closed-circuit including the first electrode 10,the nanowire 30, and the second electrode 20. Furthermore, byelectrically connecting a second storage device 80 between the first andthe second electrodes 10 and 20, the electrical energy generated by thenanowire 30 may be stored in the second storage device 80.

In FIG. 2B, an exemplary embodiment wherein a shape in which the secondelectrode 20 is bent by the stress applied to the upper portion of theapparatus for generating electrical energy is illustrated as an example.However, when a stress is applied to the first electrode 10, or when astress is applied to both of the first and the second electrodes 10 and20, the same effects may be obtained. That is, the electrical energy maybe generated by pressing or bending the apparatus for generatingelectrical energy on either, or both, sides thereof.

In order to prevent the nanowire 30 from being broken when a stress isapplied to the apparatus for generating electrical energy, an elasticmaterial (not shown) such as silicone, polydimethylsiloxane (“PDMS”), orurethane may be provided on the conductive layer 60. Here, the elasticmaterial may be formed to have a suitable thickness such that theelastic material does not prevent the nanowire 30 from being deformed bythe stress.

The piezoelectric material forming each of the nanowires 30 may havesemiconductor characteristics. For example, in one exemplary embodimenta nanowire 30 made of undoped ZnO has n-type semiconductorcharacteristics. In such an exemplary embodiment, due to thesemiconductor characteristic of the nanowire 30, a Schottky contact maybe formed on a contact surface of the nanowire 30 and the secondelectrode 20. When the Schottky contact is formed, relatively greaterelectrical energy may be obtained as compared with an embodiment whereelectrical energy is generated only by the piezoelectric effect of thenanowire 30.

As described above, when the distance between the first and the secondelectrodes 10 and 20 is decreased as a stress is applied to theapparatus for generating electrical energy, current flows due to thepiezoelectric characteristics of the nanowire 30. Therefore, electricalenergy may be generated in response to the applied stress. Furthermore,the generated electrical energy may be stored in the second storagedevice 80.

FIG. 3A(i) is a cross-sectional view illustrating another exemplaryembodiment of an apparatus for generating electrical energy, and FIG.3A(ii) is an enlarged view of the portion 3A(ii) of FIG. 3A(i).

Referring to FIG. 3A(i), the second electrode 20 of the apparatus forgenerating electrical energy may include an uneven portion A. Forexample, the uneven portion A of the second electrode 20 may have aripple-shape structure including one or more concave portions A1 and oneor more convex portions A2. In an exemplary embodiment, the unevenportion A may include a curved surface or an inclined surface. Forexample, in the exemplary embodiment illustrated in FIG. 3A, the secondelectrode 20 may include the uneven portion A of which a cross-sectionis semicircular. In the exemplary embodiment wherein the secondelectrode 20 includes the uneven portion A, the nanowire 30 may bedisposed in proximity to the concave portion A1 of the uneven portion Aof the second electrode 20.

Since the configuration of the apparatus for generating electricalenergy illustrated in FIG. 3A(i) is substantially similar to that in theexemplary embodiment described above with reference to FIG. 2A, exceptfor the shape of the second electrode 20, a detailed description thereofwill be omitted for the purpose of brevity.

FIG. 3B(i) is a cross-sectional view illustrating a state where thenanowire 30 vibrates due to a resonance in the apparatus for generatingelectrical energy illustrated in FIG. 3A(i), and FIG. 3B(ii) is anenlarged view of the area 3B(ii) of FIG. 3B(i);.

Referring to FIG. 3 b, a signal having a frequency corresponding to aresonance frequency of the nanowire 30 may be applied to the apparatusfor generating electrical energy. In one exemplary embodiment, thesignal may be applied wirelessly. In an exemplary embodiment, the signalmay be an electromagnetic wave. Further, in one exemplary embodiment thesignal may be a radio frequency (“RF”) wave. For example, in oneexemplary embodiment the RF wave may have a frequency of from about 3kHz to about 300 MHz.

The nanowire 30 may have high elasticity in addition to high tensilestrength. When a signal is applied to the nanowire 30, and the frequencyof the applied signal corresponds to the resonance frequency of thenanowire 30, the nanowire 30 may resonate due to the energy transmittedfrom the signal. For example, in an exemplary embodiment wherein theelectromagnetic wave having the frequency corresponding to the resonancefrequency of the nanowire 30 is applied to the nanowire 30, electrons ofthe nanowire 30 may be moved by the effect of an electromagnetic fieldgenerated by the electromagnetic wave. As a result, the nanowire 30 mayresonate due to the electromagnetic wave and vibrate in both directionsof the electromagnetic wave.

Since the nanowire 30 is made of the piezoelectric material, an electricpotential difference is generated in the bent nanowire 30. The nanowire30 may be disposed in proximity to the concave portion A1 of the unevenportion A of the second electrode 20. Therefore, the bent nanowire 30may be at least partially in contact with the second electrode 20. Sincethe second electrode 20 does not have a potential while the bentnanowire 30 has a potential, current may be generated between thenanowire 30 and the second electrode 20.

As described above, by applying the signal having the frequencycorresponding to the resonance frequency of the nanowire 30 to theapparatus for generating electrical energy according to an exemplaryembodiment, an electrical energy may be generated in the nanowire 30.

Although FIG. 3B(i) illustrates an exemplary embodiment in whichelectrical energy is generated by resonating the nanowire 30 in theapparatus for generating electrical energy illustrated in FIG. 3A(i),the electrical energy may also be generated from the nanowire 30 byapplying a stress to the apparatus for generating electrical energyillustrated in FIG. 3A(i). This may be understood by those skilled inthe art from the exemplary embodiment described above with reference toFIG. 2B. Therefore, a detailed description thereof will be omitted forthe purpose of brevity.

FIGS. 4A to 4F are cross-sectional views illustrating exemplaryembodiments of processes of manufacturing the portion of a firstelectrode in an exemplary embodiment of an apparatus for generatingelectrical energy.

Referring to FIG. 4A, the first electrode 10 may be formed on thesubstrate 1. In an exemplary embodiment, the substrate 1 may be asubstrate made of glass, Si, polymer, sapphire, GaN, SiC, or othermaterials having similar characteristics as described above. In oneexemplary embodiment, the first electrode 10 may be made of a conductivematerial. Exemplary embodiments include configurations wherein the firstelectrode 10 may be formed by plating, sputtering, e-beam evaporation,thermal evaporation, or other similar methods. The first electrode 10may function as the lower electrode supporting the nanowire which is tobe formed subsequently.

Referring to FIG. 4B, a nanomaterial layer 300 and nano-nuclei 301 maybe formed as a seed layer on the first electrode 10. The nanomateriallayer 300 and nano-nuclei 301 may be formed on the first electrode 10 tohave a small thickness by spin coating, dip coating, evaporation, orother similar methods. For example, in one exemplary embodiment thenanomaterial layer 300 and nano-nuclei 301 may have a thickness of fromabout 3 nm to about 50 nm. In an exemplary embodiment, the nanomateriallayer 300 and nano-nuclei 301 may be made of zinc acetate. By heatingthe substrate 1 on which the nanomaterial layer 300 and nano-nuclei 301are formed, the adhesion between the nanomaterial layer 300 and thefirst electrode 10 or between the nanomaterial layer 300 and nano-nuclei301 may be improved. For example, in one exemplary embodiment thesubstrate 1 may be heated up a temperature of about 100° C.

Referring to FIG. 4C, the nanowire 30 may be grown from eachnano-nucleus by immersing the substrate 1 on which the nano-nuclei areformed into a solution in which a nanomaterial is dissolved.

Referring to FIG. 4D, the active layer 40 may be formed on the firstelectrode 10 on which the nanowire 30 is formed. As described above, theactive layer 40 may include a material which may absorb light such assunlight and produce excitons. For example, in one exemplary embodimentthe active layer 40 may include an organic material, an inorganicmaterial, an organic-inorganic composite, or other suitable material.

Exemplary embodiments include configurations wherein the active layer 40may be formed on the first electrode 10 by spin coating, dip coating,evaporation, or other similar methods. The active layer 40 may be formedto have a suitable thickness depending on a kind of the material of theactive layer 40. For example, in the exemplary embodiment wherein theactive layer 40 made of an organic material, the active layer 40 may beformed to have a thickness of from about 100 nm to about 200 nm.

Referring to FIG. 4E, the insulating film 50 may be formed on thenanowire 30. The insulating film 50 serves to electrically separate thenanowire 30 from the conductive layer which is to be formedsubsequently. Exemplary embodiments include configurations wherein theinsulating film 50 may be formed on the surface of the nanowire 30 byspin coating, dip coating, evaporation, or other similar methods. Forexample, in one exemplary embodiment aluminum may be formed on thesurface of the nanowire 30, and be anodized, thereby forming theinsulating film 50 made of anodic aluminum oxide (“AAO”).

In another exemplary embodiment, the insulating film 50 may be made of apiezoelectric material similarly to the nanowire 30. By surrounding thenanowire 30 with the insulating film 50 made of the piezoelectricmaterial, piezoelectric characteristics of the nanowire 30 may beimproved while the nanowire 30 is insulated. For example, in oneexemplary embodiment the insulating film 50 may be made of at least oneof PZT, BaTiO₃, other suitable materials and a combination thereof.

An end portion of the nanowire 30 is not be covered by the insulatingfilm 50, but is exposed in order that the nanowire 30 may electricallycontact the second electrode when the apparatus for generatingelectrical energy has one or both substrates 1 and 2 applied with acompression force. Therefore, the insulating film 50 may be formed tohave such a height that the insulating film 50 does not entirely coverthe end portion of the nanowire 30. When the insulating film 50 isformed to cover the entire nanowire 30, a portion of the insulating film50 may be removed to expose the end portion of the nanowire 30. Forexample, in one exemplary embodiment the insulating film 50 may bepartially removed using infrared ray (“IR”) etching, plasma etching, orother similar methods.

Referring to FIG. 4F, the conductive layer 60 may be formed on theactive layer 40. Exemplary embodiments include configurations whereinthe conductive layer 60 may include metal or other similar conductivematerials. In an exemplary embodiment, the conductive layer 60 may bemade of a transparent material. Exemplary embodiments includeconfigurations wherein the conductive layer 60 may be formed to have asuitable thickness by spin coating, dip coating, evaporation, or othersimilar methods. For example, in one exemplary embodiment the conductivelayer 60 may be formed to have a thickness from about tens of nanometersto hundreds of nanometers.

Similar to the above description regarding the insulating film 50, theconductive layer 60 may also be formed to have such a thickness that theconductive layer 60 does not entirely cover the nanowire 30. When theconductive layer 60 is formed to completely cover the nanowire 30, theconductive layer 60 may be partially removed by IR etching, plasmaetching, or other suitable methods to expose the end portion of thenanowire 30.

By performing the processes described above with reference to FIGS. 4Ato 4F, the first electrode, and the nanowire, the active layer, theinsulating film, and the conductive layer disposed on the firstelectrode may be formed.

FIGS. 5A to 5G are cross-sectional views illustrating exemplaryembodiments of processes of manufacturing the portion of a secondelectrode in an exemplary embodiment of an apparatus for generatingelectrical energy.

Referring to FIG. 5A, a metal layer 200 may be formed on a templatesubstrate 3. In an exemplary embodiment, a silicon wafer may be used asthe substrate 3. In an exemplary embodiment, the metal layer 200 may bemade of aluminum (Al).

Referring to FIG. 5B, the metal layer 200 may be anodized to form ananodizing film 201. Anodizing disclosed herein may refer to the processof electrolysis in an electrolytic solution using the metal layer 200 asa cathode. Components of the metal layer 200 may be dissolved in theelectrolyte through the anodizing process, and at the same time, athickness of a natural oxide film formed on the metal layer 200 may beincreased. Therefore, the anodizing film 201 having a structure asillustrated in FIG. 5B maybe formed.

Referring to FIG. 5C, the anodizing film 201 formed through theanodizing process as described above may be removed. For example, in oneexemplary embodiment the anodizing film 201 may be removed by wetetching or dry etching. The template substrate 3 after the anodizingfilm 201 has been removed may include an uneven portion having aripple-shape structure.

Referring to FIG. 5D, a second electrode 20 may be formed on thetemplate substrate 3. The second electrode 20 may serve as an upperelectrode to be in contact with the nanowire 30 and allow current to begenerated. In one exemplary embodiment, the second electrode 20 may bemade of a conductive material. Exemplary embodiments includeconfigurations wherein the second electrode 20 may be formed by plating,sputtering, e-beam evaporation, thermal evaporation, or other similarmethods. The second electrode 20 may serve as the upper electrode to bein contact with the nanowire 30 and allow current to be generated.

In an exemplary embodiment as illustrated in FIG. 5E, an adhesion layer203 may be formed on the second electrode 20. The adhesion layer 203 maybe a layer for enhancing adhesion between the second electrode 20 and atransport substrate, which will be formed later. In an exemplaryembodiment, the adhesion layer 203 may include nickel (Ni). Furthermore,exemplary embodiments of the adhesion layer 203 may be formed byelectroplating.

Referring to FIG. 5F, the substrate 2, acting as a transport substrate,may be adhered to the adhesion layer 203. In another exemplaryembodiment, the substrate 2 may be directly adhered to the secondelectrode 20 without the adhesion layer 203. In an exemplary embodiment,the transport substrate 2 may include a polymer.

Referring to FIG. 5G, the second electrode 20, the adhesion layer 203,and the substrate 2 may be separated from the template substrate 3. Theseparated second electrode 20 may include an uneven portion A having aconcave portion A1 and a convex portion A2 due to the shape of thetemplate substrate 3.

Through the processes described above with reference to FIGS. 5A through5g, the second electrode 20 having the uneven portion A may be formed.

In other exemplary embodiments, the second electrode 20 may have asubstantially planar flat plate shape which does not have unevenportions A. Exemplary embodiments wherein the second electrode 20 have asubstantially planar flat plate shape may be formed by forming aconductive material on the substrate 2 using plating, sputtering, e-beamevaporation, thermal evaporation, or other similar methods.

FIGS. 6A(i), 6A(ii) and 6B are cross-sectional views illustratingexemplary embodiments of processes for completing the manufacture of anexemplary embodiment of an apparatus for generating electrical energy bydisposing the nanowire 30 and the second electrode 20 in proximity toeach other in a method for manufacturing an exemplary embodiment of anapparatus for generating electrical energy.

Referring to FIG. 6A(i) and FIG. 6A(ii), which is a magnified view ofthe region 6A(ii) of FIG. 6A(i), the nanowire 30 may be disposed inproximity the second electrode 20. Here, the nanowire 30 may be incontact with the second electrode 20 or may be disposed to be spacedapart from the second electrode 20. In an exemplary embodiment, when thesecond electrode 20 has the uneven portion A, the nanowire 30 may bedisposed in proximity to the concave portion A1 of the uneven portion Aof the second electrode 20.

Although FIG. 6A(i) illustrates an exemplary embodiment in which thesecond electrode 20 has the uneven portion A, alternative exemplaryembodiments include configurations wherein the second electrode 20 mayhave a substantially planar flat plate shape which does not have theuneven portion A.

Referring to FIG. 6B, the first electrode 10 and the conductive layer 60may be electrically connected to each other. For example, the firstelectrode 10 and the conductive layer 60 may be electrically connectedby way of the first storage device 70. Electrical energy generated asthe active layer 40 absorbs light may be stored in the first storagedevice 70.

Furthermore, the first and the second electrodes 10 and 20 may beelectrically connected to each other. For example, the first and thesecond electrodes 10 and 20 may be electrically connected by way of thesecond storage device 80. Electrical energy generated when the nanowire30 is bent as a stress is applied to the nanowire 30 or when thenanowire 30 vibrates as a resonance signal is applied to the nanowire 30may be stored in the second storage device 80.

While the exemplary embodiments have been shown and described, it willbe understood by those skilled in the art that various changes in formand details may be made thereto without departing from the spirit andscope of this disclosure as defined by the appended claims.

In addition, many modifications may be made to adapt a particularsituation or material to the teachings of this disclosure withoutdeparting from the essential scope thereof. Therefore, it is intendedthat this disclosure not be limited to the particular exemplaryembodiments disclosed as the best mode contemplated for carrying outthis disclosure, but that this disclosure will include all embodimentsfalling within the scope of the appended claims.

1. An apparatus for generating electrical energy, comprising: a firstelectrode; a second electrode spaced apart from the first electrode; ananowire which includes a piezoelectric material and is disposed on thefirst electrode; an active layer disposed on the first electrode; aconductive layer disposed on the active layer; and an insulating filmdisposed between the conductive layer and the nanowire, wherein thenanowire and the active layer are electrically connected to each other.2. The apparatus according to claim 1, wherein at least one of the firstelectrode, the second electrode, and the conductive layer include atransparent material.
 3. The apparatus according to claim 2, furthercomprising: a first substrate connected to the first electrode; and asecond substrate connected to the second electrode, wherein at least oneof the first substrate and the second substrate include a transparentmaterial.
 4. The apparatus according to claim 1, wherein at least one ofthe first electrode and the second electrode are flexible electrodeswhich are deformed by an applied stress, and wherein the nanowire isdeformed as a distance between the first electrode and the secondelectrode decreases, so as to contact the nanowires with the secondelectrode.
 5. The apparatus according to claim 4, wherein the secondelectrode includes an uneven portion having a concave portion, andwherein the nanowire is disposed in proximity to the concave portion ofthe uneven portion of the second electrode.
 6. The apparatus accordingto claim 4, further comprising: a first substrate connected to the firstelectrode; and a second substrate connected to the second electrode,wherein at least one of the first substrate and the second substrateinclude a flexible material which is deformed by an applied stress. 7.The apparatus according to claim 1, wherein the second electrodeincludes an uneven portion having a concave portion, and wherein thenanowire is disposed in proximity to the concave portion of the unevenportion of the second electrode and contacts the second electrode due toresonation of the nanowire in response to an applied signal.
 8. Theapparatus according to claim 1, further comprising: a first storagedevice electrically connected between the first electrode and theconductive layer; and a second storage device electrically connectedbetween the first electrode and the second electrode.
 9. The apparatusaccording to claim 1, wherein the active layer includes one of anorganic material, an inorganic material, and an organic-inorganiccomposite.
 10. The apparatus according to claim 1, wherein theinsulating film includes a piezoelectric material.
 11. The apparatusaccording to claim 10, wherein the insulating film includes at least oneselected from the group consisting of lead-zirconate-titanate, bariumtitanate and a combination thereof.
 12. The apparatus according to claim1, wherein the first electrode, the second electrode, and the conductivelayer include at least one selected from the group consisting of metal,indium tin oxide, carbon nanotubes, graphene, conductive polymer,nanofibers, nanocomposites and a combination thereof.
 13. A method formanufacturing an apparatus for generating electrical energy, the methodcomprising: disposing a nanowire including a piezoelectric material on afirst electrode; disposing an active layer, which is electricallyconnected to the nanowire, on the first electrode; disposing aninsulating film on the nanowire; disposing a conductive layer on theactive layer; and disposing a second electrode in proximity to thenanowire and substantially opposite to the first electrode.
 14. Themethod according to claim 13, further comprising: electricallyconnecting a first storage device between the first electrode and theconductive layer; and electrically connecting a second storage devicebetween the first electrode and the second electrode.
 15. The methodaccording to claim 13, wherein disposing the second electrode inproximity to the nanowires further comprises: forming a metal layer on atemplate substrate; anodizing the metal layer to form an anodized film;removing the anodizing film to form the second electrode on the templatesubstrate; joining the second electrode to a transport substrate; andseparating the second electrode and the transport substrate from thetemplate substrate.
 16. The method according to claim 13, wherein atleast one of the first electrode, the second electrode, and theconductive layer include a transparent material.
 17. The methodaccording to claim 13, wherein the active layer includes one of anorganic material, an inorganic material, and an organic-inorganiccomposite.
 18. The method according to claim 13, wherein the insulatingfilm includes a piezoelectric material.
 19. The method according toclaim 18, wherein the insulating film includes at least one selectedfrom the group consisting of lead-zirconate-titanate, barium titanateand a combination thereof.
 20. The method according to claim 13, whereinthe first electrode, the second electrode, and the conductive layerinclude at least one selected from the group consisting of a metal,indium tin oxide, carbon nanotubes, graphene, conductive polymer,nanofibers, nanocomposites and a combination thereof.